Low current igniter



Aug. 3, 1943. TOEPFER 2,325,718

LOW CURRENT IGNITER Filed July 15, 1941 fig. 1. /9

WITNESSES: INVENTOR flc/OdOh f7 Bap/er ATTORNEY 7 6f; the pojol t'o'efiect ignitioni e The apparatus shown in Fig. 1 comprises a Vhollowdouble walled-cylindrical shell'5 provided with the usual inletand .outletttubes, l and}; e through which a cooling'fiuid,such'as'water, is supplied. The shellfi may be composed of a If-theignitron-is connected to'analternating current sourcejand receives anignition impulse -.in each alternate half period, as is the usualarrangement, the next ignition impulseoccurs before themercury, returnsto its original position and either the mercury is again blown out thering or the impulse fails even 'to startan arc.

the bottom of In accordance with my invention, I provide an i'gnitronhaving an ignition electrode whose tip I plurality ofspaced-turns of awire of a material {which is wetted by the pool. The; distance be: tweenthe coil and the electrode; and the's'p'acingj. H betweensuccessiveturnsoi thcoil is suchjthat' themeni'scus of the mercury between the coil andthe electrode is substantially changed by capillary action; As a resultofthe change in .terial such as glass. A cobalt-nickel-iron alloy" 7sold .underthe trade-name of Kovar may be used 4 i i-o .gis, encircledby a coil. The coilis formed of a:

' to advantage for this purpose. 7 such as Corning G-7 AJ is sealed tothealloy ii; anda cup-shaped shell 2| of the alloy is A ring ii of glasssealed to the upper rim of the glass '59. A rod- 23 eta suitableconducting .material extends a through the center' ofthe cup Zl into theshell 5 and carries at the end within the shell a block v -Zhofthematerial, such as nickel or carbon; which functions as the anode.

l;'end*ofi,tlie'- cylinder 5 adisk ZTis welded to the:

: ie 'erte it is'provided with an'eyelet' 29 of the alloy" throughwhich'a glass exhausting tube 3| is the surface of the mercury, thecurrent required a p ior'ignition' issubstantially smaller thanin the v1 f absence of the ring; lf'thejmerciiry vapor pressure begins-f toforce the'jmer'cury betweenthe coil aridthe electrodeidownw'ard, thespace between the turns permits the vapor pressure to 7 clear apathther'ethrough whereby the cathode spot'rnay escapetofthe space abovethe surf-ace f'The use of the'coil instead of a solid ring hasthe'additional advantage of reducing the care i necessaryin positioningthe encircling member cwvith' respectto the level oi the "pool, When a 1solid ring-is usedythe top'of'the ring must be low enough to' permit theions toescape readily,

" When a coil is used, the'ions'may escape through the first spacebetween tu'rns which is above; the

: mercury.

Although I; prefer to' use a coil, a ring having a plurality of openingstherethrough may be employed; -The-size shape, and disposition of theopeningsmust be such'thatthe ring may effect asubst'antial'chang'ein'the meniscus of the-pool 7 whereby the required ignitioncurrent issu bstan tially lower than in theabsen'ce of the ring'lhesnovel features that 'I consider characteristic of my invention' areset forth v'vithp'a'rticu'.

lairity in jthe claims. The invention itseifyhowever," both as to itsorganization 'and'itsmethocl of operation, together withY'additionalobjects and advantages thereofgwillbest be understood from the followingdescription of specificembodiments when read in accompanying drawing,jin which:

-Figure' l is :a view in section showing: an ignitron in accordance withthe preferred embodimentoi my invention; I Y

FigfiZ' is an enlarged view" of the tip of I the ignition electrodeillustrating a preferred em- ,bodiinont of my inventiomf' Fig.3 is anenlargedview'illustrating a modie ficatio 'of my invention; and

Fi 4 is an enlarged View illustrating'a perfo rated ring whichmay-besubstituted I for the coil suitable etallio 'substancesuch' assteel; Near connection "with the On one side of its center the disk.

sealed. On the other side of the center of the:

disc another alloy eyelet 33 is provided and v j through'it a glasssleeve 35 extends.

thesleeve 35 an alloyrod 31 bent at right angles; at the end within theshell 5 is sealed. At its:

' horizontalendthe" rod 31 is-bent again at-righit an les, and anignition electrode 39 formedof! a;

rod o'famaterial such as boron carbidecn's'ilijoon carbide, is securedthereto.

' A coil d i formed of "a'pluralityof 'spacedturns j of a wire encirclesthetip of the electrode rod;

The wireis m ee r a material which is;

wetted by mercury, such 'as tungsten, molylodenum or other metalshavingahigh melting; point. The ends la-and; of the wire extend; on'eachside of thecoil ll and are secured to a supporting member ll by'apair. of insulators A96 and The supporting member 'fil in turn, issecured to the r0d3! by a pair of nuts 53Vand55.

/ A-suitable cathode material 51, such -as:mer- V cury, is disposed-onthe disk '21 atsuch a height that thecoil ll and the tip of therod 39extend into it. Satisfactory--operation has been 0btained by employing acoil which-is spaced from theelectrode a distanc'elofthe ordr of."3=to,3i l

mm., and inrwhich the spacing'b'etween -successive-turns is'of the'order of .Z-to 1 mm: -'Al-' though I have illustrated thecoil as i formed iof 7 wire having a'circular cross-section, it is'to be understoodthat a coil formed ofa wire orstrip having a different cross-section maybe used.

Hereinafter, the word strip is used to designate a Q 7suitablelelongated member'such as a wire.

The ex act eifect of the coil! on the meniscus of the-mercury-SI is notknowni The ignition; electrode 38 is of a'material' which is not wettedby inercuryr Thereforegintl'ie absence of the'g coil the mercuryiisdepressednear the electrode as-shown by-thedotted-line 58in Fig. 2.Since,

, the coil 4! iswetted bymercury, the surfacelofg' the cathode mercuryEltendsto' ris'eon each side;

of thecoil; .It is my theory that. the. surfacerof the mercurybetweenthev coil 4| iandthe electrode, 7 39 assumes the; shape shown bythensolidilinespfil in Fig. ,2; A greater area of thesurface ;of the,';mercuryjis then located within the boundary regionin whichthe arcdischarge takes place, Consequently, a lowercurrentcauses an are disawhi h oduc s h .r u dree o ionization. r

fere nt form which may be used in place :of the 0011,41 in Figs. 11 and2. Onerof theturnsfiiof' i tlie'electrodekt fand eachf of theremainin'g'turns' hasan" inner diameter greater than the diameter" ofthe portion ofthe electrode encircled thereby? The tight fitti'ng turn65 of the coil 83 then-sup I ports 'thecoilin position about theelectrode;

sfactol'y operation haslbeen obtained when- Througln Pmqiap r .w h i icig wneregy:

10f Figs. 1 and 2.

' explainingi my invention; ceftain itheoiieshaye 7' I boundbythesetheoii said cathode- Y V a 1 a t i i fi i i fll w ich w e a t ivot nmies e w d-a a2 i -a t can a that aspace'fexists therefiet een whichprod s distance such that the surfaceof said cathode body. I a

substanaai -chana at a hodeoitliepooF type anuen iubneieetreo atea cttothee t a WE by sameatheae ge m i afirade anw ssaeeemhererm dam on medevi'c com rising? a ooltypej' can i 'gnition electrodef -m a contactwitliksaid' and a coi mama 1 01 a,; plurality or si ns-maximu ironsawdistanee}eritheosae stee -m ni:

e)trie disenarge deviee;compnsm a h incontactiwithfsaifcathode '-saideieetfd em* ag boundary leg s; petweefi sa-ia eiecvmaewaha said J aidaie q charge to 11 in necssitatedby'the'iirior i ana bytnespififi orsure sufficient"to blowtliespot'outfth some" of G the"abrindedclairns jJ f f saidcoil c'aii befbuiit upandstill en'able t'h'e "01 1" 111Aneicthe "dischaijgefdevicje ev c'er chap-ris ng a e A r in Contactwithisaidcathode,aiidia mbe 2. In an electric discharge valve of thepool matrial wl' ichds wetted] by said: if type,"andgnition electrode[and a coil; comprising-a p conta with' said ddthddefind a coil,"comprising apiiraiaym dbeniiigsfe t d i umpd 'g -m 5 4g:p 1,circlingsaid{electrodeand nav gone oi'Tm' re ten-being spaeea n dm saidI" I saidcath'ode metre ng saidel ng k floi'x'i the inner; a pluralityof spaced turns ofa strip of a mateu c 0 its OIItBISIIIfIICG. SaidOpenings being rial substance which iswettedj by saidfcathodefl 5 1 apeand disposition and said member a encircling said electrode and spacedtherefrom in spac j d el ctrodes, distance such a distance such that theignitioncurrent required 1 that Surface id vfl between i I render saiddevice conductive is substantially member and said electrode is mod fiedby cap smallerithan in the absence or said coil. 1 ary a t h b "th -i nnt equired; 4. An electric discharge device comprising a to render saiddevice conductive is substantially a cathode of the pool type, anignition electrode in 1 contact with said cathode, and a coil,comprissmaller than in the absence of said'lbody.

in: 'a plurality of spaced turnsof a strip of a I athOde 0f t e pbotype. an ign tion electrode v substance which iswetted by said cathode,'en-n' in contact with saidcathode, saidlele ctrode being circling saidelectrode and spaced therefrom a'j Y of thetype that produces ignitionby reason of between said coil andsaid electrode is modified 1 ar re otween said electrodeand said ionization caused by an arc discharge 'inthe by capillary actionwhereby the ignitionfcurrent" e} and a rin of aaterial which is required to render" said device conductive is subwetted by Said cathode gnc rc ng said electrode stantially smaller thanin thelabsence of saidnjgjand having; a plura lity of openingstextendingfromits inner surfaceto tits outersurfacejsaid 5. An electricvdischargedevice: mmpnsmg; openings being of a size, shape and disposition-tocathode of the pool type, an ignition electrode 1 permitja cathode spotproduced by, saidarc dis:

in contact with said cathode, and aacoiLiormed charge to therethroughbefore a cathode of a plurality of spacedturns of a stripof a, subfvaporpressure sufiicient to blow the spot but the bottomroi said i s can bebuiltup, s id o en n s also'beingof such size-shape and disposition andsaid ring being spaced from said'electrode such a distancethat theignition current required to rendersaid. device Qonductive issubstantially smaller than in e bs n o sa d. em r- 1 H 12., An electricdischarge device compris ga cathode of. the pool type,; anignitionelecti'ode ineontactwiih said cathode, said electrode being ofthe type that produces ignition by reason oi ionization .,.c,aused ;byan [arc discharge5in the 1 boundary region between said electrode andsaid ';cathode,, and airing of. a material Which is wetted by; saidcathode encirclin saidelectrode and having apluralitygof openingsextending fromf its inner surf ace t 0. it outer surface said open- 1 is e n of asize. ha e a d QS i D tQ p omit some o f the ions producedbysaid are dise charge to pass therethrough beifcre a cathode .membe An. ei s ha e ev ce c m ri ins a cath ode of thepool type, an ignitionelectrode in contact with said cathode, saidjelectrode being ofthentypel that produces ignition by reason. of

ionization caused by an arc discharge in the .boundaryre gion betweensaid eleotrodeand said I cathode, and a member of a material which isyvetted by said cathode encircling said'electrode and having, aplurality of openings extending from its inner surface toitsbutersurface, said member being spaced from said electrode a distanceof the order oi .3 to 3 millimeters; said openings being of' such size,shape and disposi:

, tion to permitsoine oi the ions produced by-said arc discharge to.pass, therethrough beiore said ,arcldischarge can build upa cathodevapor pres} sure sufiicient to blow the arcout the bottom of saidencircling member and still enable said mem; .ber to effectfasubstantial modification oi the sujijfaoelof said cathode by capillaryaction, whereby the ignition current required to render the deviceconductive is substantially smaller I thanlinthe absence oisaid member.H :14, In'cQmbination an ignition electrode for cathode of the pooltype, an ignitionelectrode s member encircling said electrode and formedof one ormore openings from its inner surface to a, discharge 'device oithe pool type comprising aired of a substance suitable m'r ignitionpur-,

poses, said rod having atip adapted for immer sion in a pe r, and a coilencircling said tip'and formed of aplurality of. spaced turns ofa stripof material which is Wetted by the material of which apool is composed.I v

, 15,111 combination,anignition electrode for ,a dischargedevi'ce of thepool'typecompri'sih'g a I r'o df'ofa substance suitable forfignitionpurposes and'aboil encirclingsaid" rod 'an'dforme'd of a plurality ofspaced turns: of a fstrip which "is wetted by the materialiof which apool is'com posed, one of, said turnsl fitting' tightly about the end ofsaidrod and eachof the remaining turns having an-inner diameter greaterthan the di ameter of thep ortion of the rod encircled thereby, saidtightly fitting turn supportingsaid coil in position with thespacebetween'the' rod'and the encircling turns being no greater than 3millimeters. f ,16. In combination, anignitionelectrode' for a dischargdevice of the 15001 type comprising. a rod of asubstance suitable forignition purposes, anda'niember or" a'substancelwhichis vvetted by thematerial ofWhichfa'pooi iscomhosed, encirclingfsaid' rod and spacedtherefrom a distance ofzthe order of 3th 3 millimeters, said memberhaving one or more openings extending from its innerjsurface'to-itsouter surface. 7 v

17. An electric discharge'device comprising "a having a tip' immersed insaid cathode, and a a material which is vvetted by said cathode with itsouter surface, said member having an ,end

portion, with anfirine j' surface fitting tightly about the tip ofsaidfelectrode Itof'supportthe member thereon'with therer'nain'der. ofthe inner surface of said member spaced from said electrode T 1''18.}Anelectric discharge device comprising a cathode of the pool type,anignition rod having an end immersed insaid cathode, and av coilencircling san -0d endand formed of a plurality of .turns of a stripwhich is Wetted by said cathode, one of; said turns fitting tightlyabout saidend and supporting the coil position with each of theremaining turns having an inner diameter greater than the diameter ofthe portionof the rod encircled thereby.

ADOLPI-I Hi TOEPFE

